In recent times, wind energy installations are preferably not installed individually, but combined in groups as wind farms. Usually, such wind farms are positioned at locations which are particularly favorable in terms of wind, such as at the coast or in elevated areas. Since the individual wind energy installation nowadays already achieves powers which before were attained by entire wind farms, modern wind farms have a very high installed electrical power. The connection of such wind farms with a high power to electrical energy supply systems is not without problems. Particular attention must be paid to maintaining a high system quality. As the number of wind farms which are connected to an electrical supply system increases, stricter provisions with respect to the behavior of the wind farms on the system by the energy supply companies are required. This includes, for example, the behavior of the wind farms with respect to the system in the event of faults. An example of such faults are voltage dips, which may arise as a result of a short circuit or as a result of a sudden failure of power station power.
The wind farm master of a wind farm functions as a superordinate control system for the individual wind energy installations of the wind farm. Requirements of the operator of the wind farm as well as the operator of the energy supply system to which the wind farm is connected are in this case converted into control signals for the individual wind energy installations. This means that the wind farm, at its connection point to the energy supply system, meets the set requirements. An important function of the wind farm master is to monitor and control the power output to the power supply system, namely both true power and wattless power.
One disadvantage of this known arrangement is the fact that it sometimes responds very slowly to changed requirements. Although the wind farm master is generally provided with a sufficiently high computation power, the transmission of the control signals to the individual wind energy installations requires a comparatively large amount of time. Although generally separate communications lines are provided, considerable delays result. Typical delay times are 1 to 2 seconds for the transmission via the communications lines and a further 0.1 second for the conversion, until finally the converter can convert the signals. Owing to these long delay times, the behavior of the wind farm is not optimal in the event of changed requirements. This applies in particular in the case of rapidly changing conditions, such as gusty winds. In addition, owing to the long delay times, fluctuations in the control behavior may arise.